HURRICANE KATRINAA MOST POWERFUL HURRICANE WITH UNPRECEDENTED STRENGTH…RIVALING THE INTENSITY OF HURRICANE CAMILLE OF 1969. MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS…PERHAPS LONGER. ATLEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL FAILURE. ALL GABLED ROOFS WILL FAIL…LEAVING THOSE HOMES SEVERELY DAMAGED OR DESTROYED.THE MAJORITY OF INDUSTRIAL BUILDINGS WILL BECOME NON FUNCTIONAL.PARTIAL TO COMPLETE WALL AND ROOF FAILURE IS EXPECTED. ALL WOOD FRAMED LOW RISING APARTMENT BUILDINGS WILL BE DESTROYED.

CONCRETE BLOCK LOW RISE APARTMENTS WILL SUSTAIN MAJOR DAMAGE…INCLUDING SOME WALL AND ROOF FAILURE. HIGH RISE OFFICE AND APARTMENT BUILDINGS WILL SWAY DANGEROUSLY…A FEW TO THE POINT OF TOTAL COLLAPSE. ALL WINDOWS WILL BLOW OUT. AIRBORNE DEBRIS WILL BE WIDESPREAD…AND MAY INCLUDE HEAVY ITEMS SUCH AS HOUSEHOLD APPLIANCES AND EVEN LIGHT VEHICLES. SPORT UTILITY VEHICLES AND LIGHT TRUCKS WILL BE MOVED. THE BLOWN DEBRIS WILL CREATEADDITIONAL DESTRUCTION. PERSONS…PETS…

AND LIVESTOCK EXPOSED TO THE WINDS WILL FACE CERTAIN DEATH IF STRUCK. POWER OUTAGES WILL LAST FOR WEEKS…AS MOST POWER POLES WILL BE DOWN AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS.THE VAST MAJORITY OF NATIVE TREES WILL BE SNAPPED OR UPROOTED. ONLY THE HEARTIEST WILL REMAIN STANDING…

BUT BE TOTALLY DEFOLIATED. FEWCROPS WILL REMAIN. LIVESTOCK LEFT EXPOSED TO THE WINDS WILL BEKILLED.AN INLAND HURRICANE WIND WARNING IS ISSUED WHEN SUSTAINED WINDS NEARHURRICANE FORCE…OR FREQUENT GUSTS AT OR ABOVE HURRICANE FORCE..

I don’t think anybody anticipated the breach of the levees. They did anticipate a serious storm. But these levees got breached. And as a result, much of New Orleans is flooded. And now we are having to deal with it and will.

Much of the city is located below sea level between the Mississippi River and Lake Pontchartrain, so the city is surrounded by levees. Until the early 20th century, construction was largely limited to the slightly higher ground along old natural river levees and bayous, since much of the rest of the land was swampy and subject to frequent flooding. This gave the 19th century city the shape of a crescent along a bend of the Mississippi, the origin of the nickname The Crescent City. In the 1910s engineer and inventor A. Baldwin Wood enacted his ambitious plan to drain the city, including large pumps of his own design which are still used. All rain water must be pumped up to the canals which drain into Lake Pontchartrain. Wood’s pumps and drainage allowed the city to expand greatly in area. However, pumping of groundwater from underneath the city has resulted in subsidence. The subsidence greatly increased the flood risk, should the levees be breached or precipitation be in excess of pumping capacity (as was the case in 2005 in the aftermath of Hurricane Katrina). There were many warnings in the late 20th century that a major hurricane or a Mississippi flood could create a lake in the central city as much as 9 m (30 ft) deep, which could take months to pump dry….

…It later reached a minimum pressure of 26.64 inches (902 mbar), making it the fourth most intense Atlantic Basin hurricane on record…

Katrina was a powerful storm but there have been in recorded history (the last 200 years or so) at least 3 storms that would have done the same thing to New Orleans if they hit their mark. So… there is a levee-breaking storm every 50 years…. and such a storm might hit it’s mark right over New Orleans 1 in … I don’t know … 1 in 10 times.

I’ve heard it said that it was known that the levees were rated to protect against a class 3 hurricane (I googled around a little for a definitive text on this but couldn’t find one [reference found, see below – Lee]). That simply isn’t adequate protection for an area that routinely (every 10-100 years) gets hit by larger storms.

To counter one friend’s ridiculous accusation that this catastrophe happened because of global warming, I must insist that it was just simple probability. Anyone who knew anything about the levees knew that every hurricane coming in from the gulf was a roll of the dice.

The Army Corps of Engineers has said that Katrina was just too massive for a system that was not intended to protect the city from a storm greater than a Category 3 hurricane… The event exceeded the design…

The article goes on to to talk at length about how the design of the floodwalls may have been faulty but at the same time, they reiterate that it wasn’t designed to handle a storm as large as Katrina.

Nicely composed argument. It’s a shame though how much backing the “we couldn’t have predicted this” side is getting in the press. My impression though is that most people I talk to (outside of Boston) aren’t buying the President’s line. The group within Boston, well, there are other forces at work here so I have to discount them.